Source vs GameGuru

Valve's official documentation website is great for newbies. It demonstrates the pros and cons of the engine (and since the website isn't maintained by Valve, but instead the community, the pros and cons are largely unbiased). There are also a number of pages dedicated to entities used within official Valve games and also community-made mods that were turned into full-fledged games by Valve. These pages explain the ins and outs of how most source programming works. There are also guides for Valve's tools which are both included in Source SDK and in any Valve-developed game.

Since it has precalculated lighting, this engine is great for low end PCs too.

You don't need to code your own door or ladder etc. You can pretty much use every entity used in Half-Life 2 yourself easily.

Of course you can program stuff into source but for level design only, source has a really easy input/output system for your level logic (e.g. doors, trigger when player walks into room...).

Source includes Source Filmmaker, a video capture and editing application.

Simplicity and accessibility are the core design goals of FPS Creator Reloaded.

Users share ideas, help, and advice through the official forums. The community also provides a wealth of free assets, and the GameGuru Assets Store sees constant additions.

News and improvements are released on a monthly schedule. Interaction between The Game Creators and project backers is excellent.

Easily import your own 3D models with the built-in importer and create custom characters with the Character creator. Custom weapons are much more difficult, though.

The gamer creator forums have a large number of users, developing games, making models for sale and to give away for other users. They answer questions, help each other with problems in their games, and can make using this software so much more fun and easy.

Games you publish with GameGuru can be sold without any restrictions or commissions.

An easy 3D editor to create your own maps in seconds with drag-and-drop function.

Awesome friendly GUI, and quite easy to use.

Currently in development but already looking very good! Easily create big and customized buildings with default building blocks and share them with others.

Also very easy to use in the designer: The buildings are treated like entities but still directly available in the 'building editor mode'.

Uses Lua.

A store where you can buy various assets for your games like sounds, 3D models, weapons... Very good prices and a lot of assets are even free.

The Game Creators team frequent the forums and ask the community for feeback and suggestions both there and via an open poll on the website. They have a great history of reading suggestions, viewing screenshots, and generally working with the community.

The game engine is optimized for efficient use of memory.